Get the Sennheiser IE-800. It's $300 dollars less expensive and it has a detachable cable at the Y cable section which makes it semi user replaceable in case they break. Single ultra wide dynamic drivers sound superior to multi-driver balanced armature and bass dynamic driver technology with no frequency or phase incoherence. Even my Ultimate Ears Ue-18 PRO custom IEMs exhibit frequency incoherence with their 18 balanced armature drivers. The only reason why I want the AKG K3003i is because I have the money and I love the AKG brand more than Sennheiser. I'm a collector at heart. I am very brand loyal. I am also loyal to a trusted authorized dealer which in my case is HeadRoom Corporation.

Otherwise, the IE-800 is going to sound more balanced and coherent than the K3003i. They're also easier to achieve a tight seal inside your ears than the K3003i because they come with more different sized ear tips. The IE-800 is also smaller and lighter than the K3003i.

Both are still accurate and neutral, but I'd give the edge to the K3003i. I have the Etymotic ER-4PT with the 4S adapter and I found that the K3003i to be more accurate and neutral with higher resolution and more detail retrieval, but less passive sound isolation. The IE-800 is much superior to the ER-4S in almost every category except for passive sound isolation and price.

What Sennheiser said is true. The IE-800 competes with their HD-600, HD-700, and HD-800, but it offers portable audiophile sound performance on the go. They compare to full sized open design headphones at similar prices and they offer competitive sound performance. The AKG K3003i takes the K 701, K 702, and Q 701 sound and it simply refines everything with a hybrid multi driver design. They do sound eerily similar to the Sennheiser HD-800 except they aren't as finicky with regard to pairing it with a suitable headphone amplifier. They can be driven by portable DAPs like the Apple iPod Touch or Classic or iPhone 5.

These top of the line IEMs work best with a home reference system for maximum sound performance. They scale well with upscale and top of the line reference audio systems at home. The sound is exquisite. If you can tolerate the universal fit, then they are simply unbeatable at this moment. I'd still go with the AKG K3003i. I still have them on extended loan and audition right now.

They are unbelievable. It's like taking the AKG K 701, K 702, and Q 701 and shrinking them down to tiny IEMs. At first listen, they don't sound very special, but they are indeed very special. They don't wow you with instantly identifiable sonic signature. Instead, they let the music flow through virtually colorlessly and you get sucked into the music. The music speaks loudly for itself. These are the best universal IEMs that I have ever heard. They are far superior to the ER-4S.

The AKG K3003i is an ultra high end reference grade universal in-ear monitor. It's priced at $1,300 dollars. It takes the AKG K 701, K 702, and Q 701 sound to the extreme by focusing on a clean, accurate, neutral, and transparent mid range and fanning out to the bass and treble region with evenhanded tonal balance. For some listeners, it may sound peaky in the upper treble region, but that's indicative of the AKG house sound. It has a lean, analytical, clinical sound that lets the music speak directly for itself. Unlike the AKG K 701, K 702, or Q 701, the K3003i has a more pronounced deep bass that is tighter, quicker, more highly textured, and it has more impact than the full-sized open design reference headphone does. It features a hybrid bass dynamic driver and two balanced armature mid range and tweeter drivers. Like most multi-driver designs, it does suffer ever so slightly from frequency incoherence and phase distortions, but the only way you'll hear such imperfections is if you use very well mastered high resolution test tracks of which you are intimately familiar such as 24 bit 192 kHz loss less files. The passive sound isolation is fair for most ambient noise, but it does not offer sufficient noise blockage in very noisy environments such as construction sites, subways, live concerts, and trains or airplanes. They are pretty sensitive so they can be easily driven from an Apple iPhone 4s or earlier or an Apple iPod Classic or Touch or an Apple iPad 3rd generation. It comes with an inline volume control and microphone that works on older Apple iOS and OS X devices. I used the reference filters most of the time, but I did try the bass boost and treble filters and I didn't like them. The fit and finish is superb. The box is handsome and worthy of keeping as a collector's item. It comes with a genuine leather carrying case. The cables are non-removable.

Comparing these to the Sennheiser IE-800, it's much more difficult to pick out a clear winner. These two top of the line universal IEMs use completely different technologies. I'd say that the IE-800 has to be the more popular choice among audio professionals and rich audiophiles because it is a better known brand and it's $300 dollars less expensive and it comes with a user detachable cable at the Y split. The IE-800 has strong bass impact that's well articulated, taut, snappy, and it delivers excellent slam due to the resonance filter and the unique double bass ports at the back. It's easy to see why they would be the more popular choice especially among purists that believe a single ultra wide dynamic driver is superior to a hybrid multi-driver design. To a certain point, they are right. The only reason why the hybrid design is superior is increased focused clarity, purity, accuracy, neutrality, resolution, transparency, detail retrieval, micro dynamic shading, and a wider dynamic range. The IE-800 has a much wider frequency range than the K3003i, but the K3003i is better suited for audiophiles that want a portable reference grade sound performer in as tiny of a package as possible. I'd give the slight edge to the AKG K3003i if you value purity and clarity and transparency more than the deep bass power of the IE-800. The K3003i has more evenhanded tonal balance than the IE-800, but it's slight and it comes down to personal preferences. I felt that the real key difference is in the mid range with the K3003i delivering a purer and more analytical mid range that sounds quite exceptional whereas the IE-800 is merely excellent. The K3003i is focused on the mid range in particular whereas the IE-800 trumps it with its solid bass foundation. Again, the differences were slight and it comes down to personal preferences at this level.

I feel that these compete well with top of the line headphones like the Sennheiser HD-800, HD-700, AKG K 702, Beyerdynamic T1, etc. You sacrifice that out of head sound stage with IEMs, but it's more intimate and focused. It's a private listening studio inside your head with the K3003i or IE-800. I feel that it's better to spend the money on top of the line universal or custom in-ear monitors because portability is a key enabling factor. I never saw anyone travel with Sennheiser HD-800 headphones in my travels. I keep my AKG K 702 at home.

Finally, the better your source music, the better these top of the line IEMs will scale. High resolution loss less audio files are mandatory with the IE-800 or K3003i. I have a limited 31 gigabytes of FLAC 24 bit 192 kHz files while the rest of my music library consists of Fraunhofer or LAME 3.99 --preset-insane 320 Kbps CBR MP3s. Listening to MP3s or Spotify Premium using Vorbis 320 Kbps with the IE-800 or K3003i is futile. You're not going to get the maximum sound performance using lossy codecs period. It's a lot less expensive and more sensible to use lower end universal IEMs like Etymotic ER-6i or HF5 or Ultimate Ears Ue-700 or Super.Fi TF-10. It makes me wish that I had an iRiver AK100 Astrell and Kern digital audio player with 160 gigabytes of flash storage to store my 24 bit 192 kHz FLAC files. I do have a full backup of my FLAC library in my CrashPlan+ account in their data center, but it would be terribly expensive for me to re-purchase my entire music library at high resolution.

I performed almost all of my critical listening sessions at home. At this point, it's clear that the IE-800 and K3003i belong outside of the home on the go with an Apple iPhone or iPod or iPad. After thinking very hard about the $1,300 dollar price tag and $1000 dollar price tag respectively for the K3003i and IE-800, I think that I will return both for full refunds. To be quite honest and truthful, I don't do critical listening sessions outside of my home. I rarely take my System76 Lemur Ultra Thin notebook PC outside of my home because it is a US DoD hardened PC with confidential data. It doesn't make much sense for me to spend $2600 for two top of the line IEMs since their intended applications fall outside of my case usage. I can easily think of better things to do with that kind of money like paying bills that would be put to better usage.

I thank Crutchfield for helping me to acquire both the Sennheiser IE-800 and AKG K3003i for review. They have a generous 30 day guarantee.

I don't think I have a need for any more headphones or IEMs. I'm pretty satisfied with what I have got and they meet my case usage and they're eminently affordable.

I can't get no respect. I put the effort to share my opinions about two top tier UIEMs and I get this in return?

Buy them yourselves and write something better.

I found small differences between the IE-800 and K3003i. To make things more interesting, I found small differences between the Etymotic ER-4PT/S combination and the IE-800 and K3003i. When people talk about one not being in the same league as the other two, I'd have to say that they're exaggerating the truth which is typical fare in this forum because people don't tell the truth. Everything is night and day difference which is total b u l l s h i t ! ! ! The ER-4S gets you about 92 - 95% of the IE-800 or K3003i sound for a fraction of the price. I think that both of them are overpriced for UIEMs. I'd rather get a full sized pair of headphones for the same price.

K3003i is for people that have money to burn. It's a nice product, but it is in no way worth its street price or full MSRP.

It really depends on what your ears are trained to hear. I hear some kind of compression on BA based phones that I don't hear on dynamic phones. That thing sometimes bothers me (when I compare them with full sized hi end dynamic phones, for instance). OTOH I'm hoping to discover a dynamic IEM that can provide a similar amount of detail.

But for the average listener I admit that all that stuff is not crucial and can seem like they don't need it.

Leslie, your last posts in this thread are somehow contradictory, maybe you should re-read them and try to be more consistent.

Quote:

"They are unbelievable. It's like taking the AKG K 701, K 702, and Q 701 and shrinking them down to tiny IEMs. ...

... they let the music flow through virtually colorlessly and you get sucked into the music. The music speaks loudly for itself. These are the best universal IEMs that I have ever heard. They are far superior to the ER-4S."

And then:

"The ER-4S gets you about 92 - 95% of the IE-800 or K3003i sound for a fraction of the price."

The AKG K3003i is an ultra high end reference grade universal in-ear monitor. It's priced at $1,300 dollars. It takes the AKG K 701, K 702, and Q 701 sound to the extreme by focusing on a clean, accurate, neutral, and transparent mid range and fanning out to the bass and treble region with evenhanded tonal balance. For some listeners, it may sound peaky in the upper treble region, but that's indicative of the AKG house sound. It has a lean, analytical, clinical sound that lets the music speak directly for itself. Unlike the AKG K 701, K 702, or Q 701, the K3003i has a more pronounced deep bass that is tighter, quicker, more highly textured, and it has more impact than the full-sized open design reference headphone does. It features a hybrid bass dynamic driver and two balanced armature mid range and tweeter drivers. Like most multi-driver designs, it does suffer ever so slightly from frequency incoherence and phase distortions, but the only way you'll hear such imperfections is if you use very well mastered high resolution test tracks of which you are intimately familiar such as 24 bit 192 kHz loss less files. The passive sound isolation is fair for most ambient noise, but it does not offer sufficient noise blockage in very noisy environments such as construction sites, subways, live concerts, and trains or airplanes. They are pretty sensitive so they can be easily driven from an Apple iPhone 4s or earlier or an Apple iPod Classic or Touch or an Apple iPad 3rd generation. It comes with an inline volume control and microphone that works on older Apple iOS and OS X devices. I used the reference filters most of the time, but I did try the bass boost and treble filters and I didn't like them. The fit and finish is superb. The box is handsome and worthy of keeping as a collector's item. It comes with a genuine leather carrying case. The cables are non-removable.

Comparing these to the Sennheiser IE-800, it's much more difficult to pick out a clear winner. These two top of the line universal IEMs use completely different technologies. I'd say that the IE-800 has to be the more popular choice among audio professionals and rich audiophiles because it is a better known brand and it's $300 dollars less expensive and it comes with a user detachable cable at the Y split. The IE-800 has strong bass impact that's well articulated, taut, snappy, and it delivers excellent slam due to the resonance filter and the unique double bass ports at the back. It's easy to see why they would be the more popular choice especially among purists that believe a single ultra wide dynamic driver is superior to a hybrid multi-driver design. To a certain point, they are right. The only reason why the hybrid design is superior is increased focused clarity, purity, accuracy, neutrality, resolution, transparency, detail retrieval, micro dynamic shading, and a wider dynamic range. The IE-800 has a much wider frequency range than the K3003i, but the K3003i is better suited for audiophiles that want a portable reference grade sound performer in as tiny of a package as possible. I'd give the slight edge to the AKG K3003i if you value purity and clarity and transparency more than the deep bass power of the IE-800. The K3003i has more evenhanded tonal balance than the IE-800, but it's slight and it comes down to personal preferences. I felt that the real key difference is in the mid range with the K3003i delivering a purer and more analytical mid range that sounds quite exceptional whereas the IE-800 is merely excellent. The K3003i is focused on the mid range in particular whereas the IE-800 trumps it with its solid bass foundation. Again, the differences were slight and it comes down to personal preferences at this level.

I feel that these compete well with top of the line headphones like the Sennheiser HD-800, HD-700, AKG K 702, Beyerdynamic T1, etc. You sacrifice that out of head sound stage with IEMs, but it's more intimate and focused. It's a private listening studio inside your head with the K3003i or IE-800. I feel that it's better to spend the money on top of the line universal or custom in-ear monitors because portability is a key enabling factor. I never saw anyone travel with Sennheiser HD-800 headphones in my travels. I keep my AKG K 702 at home.

Finally, the better your source music, the better these top of the line IEMs will scale. High resolution loss less audio files are mandatory with the IE-800 or K3003i. I have a limited 31 gigabytes of FLAC 24 bit 192 kHz files while the rest of my music library consists of Fraunhofer or LAME 3.99 --preset-insane 320 Kbps CBR MP3s. Listening to MP3s or Spotify Premium using Vorbis 320 Kbps with the IE-800 or K3003i is futile. You're not going to get the maximum sound performance using lossy codecs period. It's a lot less expensive and more sensible to use lower end universal IEMs like Etymotic ER-6i or HF5 or Ultimate Ears Ue-700 or Super.Fi TF-10. It makes me wish that I had an iRiver AK100 Astrell and Kern digital audio player with 160 gigabytes of flash storage to store my 24 bit 192 kHz FLAC files. I do have a full backup of my FLAC library in my CrashPlan+ account in their data center, but it would be terribly expensive for me to re-purchase my entire music library at high resolution.

I performed almost all of my critical listening sessions at home. At this point, it's clear that the IE-800 and K3003i belong outside of the home on the go with an Apple iPhone or iPod or iPad. After thinking very hard about the $1,300 dollar price tag and $1000 dollar price tag respectively for the K3003i and IE-800, I think that I will return both for full refunds. To be quite honest and truthful, I don't do critical listening sessions outside of my home. I rarely take my System76 Lemur Ultra Thin notebook PC outside of my home because it is a US DoD hardened PC with confidential data. It doesn't make much sense for me to spend $2600 for two top of the line IEMs since their intended applications fall outside of my case usage. I can easily think of better things to do with that kind of money like paying bills that would be put to better usage.

I thank Crutchfield for helping me to acquire both the Sennheiser IE-800 and AKG K3003i for review. They have a generous 30 day guarantee.

I don't think I have a need for any more headphones or IEMs. I'm pretty satisfied with what I have got and they meet my case usage and they're eminently affordable.

Mr Leslie Dorner,

Very well written and informative response to the OP. I also own the K3003 (no "i" because I agree with you that at that level it is not sensible for me to listen outside of the home). I like comparing the 3003 to some of my other gear using my Ressy (Resonessence Labs Invicta) and the various other toys I have. I particularly agree with you about issues of coherence in your comparisons to the Senn IE800 using a single dynamic driver vs the hybrid design of the 3003 or the other multi Ba designs that you've mentioned. Clearly, you have come a long way as an audiophile and your choices indicate that you are a matured and sensible listener.

I've got to be crazy enough to get the AKG K3003i instead of the Sennheiser HD-800, but it's a part of my mobile audio system setup. I got a System76 Lemur Ultra Thin (lemu4) with Ubuntu 13.04 64 bit GNU/Linux and I also got a Western Digital My Passport 2 TB USB 3 Portable hard disk drive where I store my multimedia library. I heard both of them and I prefer the K3003i because they're really portable and high end for UIEMs or any IEMs for that matter. I really love the AKG house sound too. The HD-800 requires more of a substantial investment in upstream components to sound their best and they can be finicky with the headphone amplifier.

I plan to get a Meridian Explorer to go with the AKG K3003i next year when I have extra funds. I haven't heard it yet, but I plan to make a trip to an authorized Meridian dealer by the end of this year to audition it.

I want to be able to travel on the road and take an ultra high end mobile audio system with me. I plan to watch lots of movies, videos, and I am going to listen to tons of music. This should do the trick for me.